I have always hated throwing away single-use jar lids and rusty screw bands. Replacements are costly, and as public awareness of the need to live more sustainably grows, the idea of disposable jar components becomes increasingly absurd. So I was pleasantly surprised to receive an email from Lukas Boettger. Lukas explained that he worked for a company called Pearl. They were going to revolutionise the world of preserving with their new range of Jars. Pearl Jars feature reusable closure systems. Would I like to stock them? It didn’t take much of an argument to persuade me.
Introducing Pearl Jars
Pearl’s jars are similar in size and shape to regular Mason jars, such as those made by Ball and Kilner. The principal differences are the lid components, which are meant to last the entire life of the jar, and the rubber seals, which can be reused numerous times. There are four types of jar in the range, each with a different closure system:
Pearl Luna Cap Preserve Jars
The Luna Cap is the flagship of Pearl’s range of jars. Like other modern Mason jars the closure consists of a screw band and lid disc. However, unlike other canning jars, the band and lid are constructed of rust-free and fully reusable stainless steel.
Luna Cap jars are available in 0.25 litre, 0.5 litre and 1 litre sizes.
Pearl Sunny Cap Preserve Jars
The Sunny Cap Jar design takes its inspiration from older Mason jars designed prior to the adoption of metal lids. The jars themselves are identical to the Luna Cap but feature a closure consisting of a stainless steel screw band and thick glass lid. The lid is interchangeable with that of the Mariposa jar.
Sunny Cap jars are available in 0.25 litre, 0.5 litre and 1 litre sizes.
Pearl Classic Swing Preserve Jars
The Classic Swing Jar has a hinged glass lid and a traditional stainless steel clip-top wire closure mechanism. These attractive jars are designed for canning but are also ideal for dry storage of spices, pulses, and the like.
Classic Swing jars are available in 0.5 litre and 1 litre sizes.
Pearl Mariposa Preserve Jars
The Mariposa is the most unusual jar in the range, with a stainless steel wire mechanism clamping down on a removable glass cover. This simple and elegant closure is inspired by the Lightning Preserve Jars of the late 19th century. The lid is interchangeable with that of the Sunny Cap jar. In addition to canning, these jars are ideal for fermenting. As carbon dioxide builds up from the ferment they will open periodically in response to the pressure. No ‘burping’ is required.
Mariposa jars are available in 0.5 litre and 1 litre sizes.
Testing the Jars
Having received our first batch of jars from Pearl I got down to testing them. I followed our spiced red cabbage canning recipe and made a number of batches using the full selection of 0.5 litre jars in the Pearl range.
The Mariposa and Classic Swing jars performed excellently throughout the tests with every single jar sealing well after removal from the water bath canner.
Initially I used the traditional “finger tight” method for closing the Luna Cap jars prior to canning. From this first batch a number of jars failed to form a proper vacuum seal following the canning process. Having discussed the matter with Pearl it transpired that the jars need to be screwed closed properly prior to canning. Having taken that advise the second batch of Luna and Sunny Cap jars sealed with a 100% success rate.
In our tests The Sunny Cap jars performed well when used for canning however as there is no tab on the rubber seal they require levering open with a blunt knife or similar tool. For this reason Pearl recommends all the jars apart from the Sunny Cap for use in both water bath and pressure canners.
To help transitioning to this excellent new range of jars I have created a post which contains instructions on how to use Pearls range of jars for canning.
Having experimented with all four of the jar closures myself I then distributed more jars amongst our local preserving community for further testing. In addition to water bath canning we have put the jars to other uses such as fermenting sauerkraut, making strawberry jam, pickling shallots, storing wild garlic pesto in the freezer an as airtight containers whole spices and pulses.
The response from our test group was overwhelmingly favourable. I posed a few questions to Lukas at Pearl based on the feedback received.
Lukas, what inspired Pearl to develop the range of preserve jars and what drove your choice of materials to use?
We wanted to produce a range of canning jars with reusable lids. Throwing lid components away is expensive and unsustainable. Stainless steel parts with separate seals was the best option. Stainless steel is food safe and corrosion free without having to coat it or produce a laminate material that would be hard to recycle. By having separate and replaceable seals we can also avoid having to use an adhesive on the lids.
Are you a keen preserver yourself?
Yes, I’m fascinated by preserving and do a lot at home. More fermentation than canning though.
Where are Pearl jars manufactured?
Pearl is based in Lisbon, Portugal but the jars are made in Spain by our partners at Estal. The rubber seals are also made in Europe while the stainless steel components are imported from Asia.
From conversations I have had with you late last year I remember that initially the plan was to use TPE seals that would last the lifetime of the jars. What happened to that goal?
TPE is a great food-safe material. It is one of the few plastics that can be reformed into something new with no material degradation simply by heating, essential for closed loop recycling. It is also extremely hard wearing. Unfortunately at the temperatures obtained in canners we found that the TPE seals can become soft and deform. They are still available for storage or fermentation use but we now recommend that only the natural rubber seals are used for canning.
How often will the natural rubber seals need replacing?
They are designed for multiple uses but it depends on a number of factors. High fat foods, for example, tend to degrade the rubber a lot faster.
Are replacement seals available?
Yes, they will be.
Are the natural rubber seals biodegradable or recyclable?
Unfortunately not due to the processing needed to make rubber products. They are however sustainable in terms of the natural latex rubber used in their manufacture.
I passed a selection of Pearl jars out to members of our local community for testing. The feedback has been amazingly positive. The diversity of the range though did cause some confusion at first. Why have Pearl developed four types of closure system?
Each jar type is unique and has it’s own advantages for a particular use whether that is dry storage, canning or fermenting.
Can all the different types of Pearl jar be used for water bath and pressure canning?
Yes, apart from the Sunny Cap jars. The Sunny Cap jars require some external leverage to open the lids when vacuum sealed, and we cannot recommend anyone does that in case they break the jar or hurt themselves. They are great for storage and fermentation though.
The Luna Cap range of jars in particular seem aimed as a direct replacement for Kilner and Mason canning jars. They have been designed with a similar system of lid and screw-band. With the old traditional jars the advice is always to ‘finger tighten’ the bands prior to canning. We found that the Luna jars failed to seal properly if this approach is taken, instead the bands needed to be screwed down fully. Is this the correct way to use the jars?
Yes, that is correct. Tighten fully but no need to over-tighten. You get a great seal with the Luna Cap jars after canning. There is cut-out on the lid disc to allow you to easily break the vacuum seal and lever open the jars with your fingers.
People from our test group were extremely impressed with the Luna Cap but it is the Mariposa jars that has garnered the most affection. Do you have a personal favourite from the range?
Yes, the Mariposa as well. It looks great and because the wire is removable and the lid is separate it is very easy to clean. When fermenting, the wire bail mechanism lets out the gases when the pressure inside the jar builds up so there is no need to manually release them.
So what is next for Pearl?
The jars are still very new and we are working really hard to raise brand awareness right now. We have lots of plans for more sustainable products in the future and have just launched our new Philos glass water bottle. It’s the first industrially produced product of its kind made from 100% post-consumer recycled glass.
A Brief History of the Canning Jar
In 1858, John Mason patented the first screw-top jar closure. The single piece lids were constructed of reusable, corrosion resistant, zinc alloy with a replaceable rubber seal. Previously, jars had been sealed chiefly with wax.
Hugely popular, Mason’s eponymous jar inspired a boom in home canning. The success of his jars led to the production of many imitations, and the introduction of further innovations. Zinc alloy lids would often lend a metallic taste to a jar’s contents. This resulted in the widespread adoption of jars with glass lids and either a separate metal screw-band or a spring-clip system to hold it in place.
Today, most canning jars still feature a screw-band but use a disposable metal lid with a food-safe coating and affixed rubber gasket. Jars of this type are available from well known brands such as Ball, Kilner, Kerr and Leifheit. First introduced by Kerr in 1915, jars with this reliable closure system have dominated the world of home canning for over a century.
But things are moving on. Strongly influenced by the evolution of the Mason Jar, Pearl has resurrected and improved upon historical designs using contemporary materials and manufacturing processes. By challenging the paradigm of disposability, Pearl is building on the great tradition of innovation first instituted by John Mason.